Diagnosis of Viral Infections Flashcards
How can you detect the presence of a virus?
Electron microscopy, detection of cytopathic effect, PCR and other nucleic acid amplification tests
What are positives of PCR?
Fast and very sensitive
What are negatives of PCR?
Vulnerable to laboratory contamination, need to know virus sequence beforehand
What type of antibody does serology detect and how is this possible?
It detects IgM. After infection, IgM appears and remains positive for up to 12 weeks after acute infection
What swab do you use for bacterial infection?
Black charcoal
What swab do you use for viral infection?
Green
How can you detect EBV using an FBC?
Do a blood film and it should show atypical lymphocytes and expansion of CD9 T cells
What test do you use to detect the levels of IgM?
ELISA
What is the cut off for significant EBV IgM?
1/64
What Ig is IgM replaced by as infection persists?
IgG as it is more effective
What caused infectious mononucleosis?
EBV
What is infectious mononucleosis also called?
Glandular fever
How long does it take for EBV films to be ready?
Hours
How long does it take for EBV PCR to be ready?
Next day
How long does it take for acute EBV serology to be ready?
1-2 days
What are some symptoms of infectious mononucleosis?
Fatigue, malaise, tonsils red/swollen/white patches, throat sore/red, cough, fever
What viruses does a respiratory PCR look for?
Influenza A/B, RSV, Parainfluenza 1-4, Human metapneumovirus, rhinovirus, coronavirus, adenovirus
How long does respiratory PCR take?
More than 24 hours
What should you do while waiting for respiratory PCR results?
Isolate patient and treat with neuraminidase inhibitors
What is quantitative PCR?
It tells you the amount of DNA/RNA present
What is the Ct value in quantitative PCR?
The point at which fluorescence is detectable above baseline
What does a lower Ct value indicate?
More DNA/RNA is present
What is the first test done in HIV screening?
COBAS Ag/Abs screen
What are the second tests done in HIV screening if the first test is positive?
Liaison X and Geenius line assay
